Author response table 1.

	Original data in manuscript	Data in independent replicate	Modifications made in the manuscript
Figure 1A	Acylcarnitines derived from amino acids, C3 and C5, were significantly reduced in D12 GRU102	Only C3 was significantly reduced in D12 GRU102; C5 showed a trend towards reduction but the difference did not reach statistical significance in D12 GRU102	We removed the sentence stating that C5-Acylcarnitine was significantly reduced and focused only on C3-Acylcarntine: “AA-derived AC species (C3-carnitine) was also significantly reduced in old GRU102 (Figure 1A), suggesting that AA metabolism was affected in old GRU102.”
Figure 1D	Percentage of amino acids forming pyruvate were significantly lower in both D4 and D12 GRU102 Percentage of amino acids forming aKG were significantly higher in both D4 and D12 GRU102	Reduction in percentage of amino acids forming pyruvate did not reach statistical significance in both D4 and D12 GRU102 Increase in percentage of amino acids forming aKG was only statistically significant in D12 GRU102, but not in D4 GRU102	We removed the phrase that the percentage of amino acids forming pyruvate was significantly lower and focused only on the increase in percentage of amino acids forming aKG: “This analysis of the AA profile demonstrated that, in comparison to age-matched controls, the percentage of glucogenic AA forming alpha-Ketoglutarate (aKG) was significantly increased in old GRU102 animals (Figure 1D).”
Figure 5D	Metformin significantly increased levels of Ala, Asp, Gly, Leu, Met, Phe, Pro, Ser, Trp and Val in D12 GRU102.	Metformin significantly increased levels of Ala, Asp, Gly, Phe, Pro, Ser while significantly decreased levels of Arg and Tyr in D12 GRU102.	The general trend that Metformin increased levels of several individual amino acids still holds, even though the two replicates showed a slight variation in the identity of amino acids that were increased. We have modified our wording as follows: “We found that Metformin treatment increased the abundance of many AA in GRU102, with Alanine, Glycine, Proline and Serine consistently increased in both replicates (Figure 5D, Figure 5—figure supplement 1).”
Figure 5E	Metformin significantly increased levels of C3-acylcarnitine and also C5-acylcarnitine, even though the latter did not reach statistical significance.	Levels of C3-acylcarnitine appear similar between Metformin-treated and untreated GRU102. Metformin also appears to reduce the levels of C5-acylcarnitine, even though the reduction did not reach statistical significance.	Given the different trends observed in the two replicates, we feel that the increase in C3-acylcarnitine originally observed was within the noise of the measurement, and hence has removed its discussion in the manuscript.